Apparatus for indicating the depth of liquid in vessels



L. MURPHY. APPAnATus ron mmcATme THE DEPTH or LIQUID m VESSEL'S.

APPLICATION FILED JULY I5. 1918.

Patented Feb. 8, 1921.

\H IHBH I I I F A mw m construction the possibility occurs that, it

LEONARD MURPHY, 0F DUBLIN, IRELAND.

APPARATUS FOR INDICAIING TH E DEPTH 0F LIQUID IN 'VESSELS.

Specification of Lettersiatent.

Patented Feb. 8, 1921.

Application filed July 15, 1918. Serial No. 245,028.

Vessels of which the following is a speci-.

fication.

In Letters Patent No. 867994: of 1907 I have described an apparatus for indicating the depth of liquid ina tank or other .re-

ceptacle by forcing air or other gas into a gage or gage reservo1r unt1l thG GHBCUVG pressure on the indicating liquid was that a due to the depth of liquid in the vessel to be gaged, the gas being introduced into the gage through a tube dipping into the indicating liquid which automatically sealed the apparatus against lealrage of the gas, any excess gas escaping through the open end of the line tube whichreached to the bottom of the vessel to be gaged.

In one form of the apparatus the indicating parts of the instrument were separated from the sealing chamber. so that. no evaporation of the indicating liquid could occurwhen air or other gas was forced through it.

The airwas forced by the compressor" through a tube dipping below the surface of mercury and escaped by a pipe leading to the indicator and to the line tube. In this the line tube is inadvertently closed, the air pressure may exceed the capacity of the indicating column of liquid, which-would in consequence be forced out, or a spring pressure gage might be seriously strained.

I surface of According to the present inventilon, this danger is obviated by a device by which the liquid in the sealing chamber ceases to act as a seal when a predetermined pressure is reached. For this purpose a verticail safety tube open at the upper end is connected at its lower end with and the chamber are so proportioned. that when the air pressure reaches a predeter mined value sufficient liquid has passed from the seal chamber into the safety tube to uncover the end of the tube 'which supplies the air pressure and normally dips below the the liquid. When the end of the tube is uncovered the compressed air flows back into the compressor after each stroke.

In the accompanying drawings Figures 1-3 show the action of a device according to the liquid in the seal chamber and the cross sections of the tube the invention respectively, in three stages of the process.

Fig. lshows a measuring instrument according to the invention with various forms of indicating apparatus.

In the examples shownv the air pressure is provided by a cylindrical tube A closedat the upper end, the lower end dipping into a liquid contained in the vessel B. A compressor tube C having its upper open end extending to the upper end of the vessel B has its lower end extending into a sealing chamber D, so that the liquid in the sealing chamber D (mercury, for example) normally closes the lower end of said tube. The air pressure generated at each downward stroke of the tube A isconveyed by the tube C to the sealing chamber D. A safety tube E open at the upper end communicates as'shown with the lower portion ofthe sealing chamber. The air pressure is conveyed by a pipe F to cocks G connected respectively by pipes. H with the vessels K (see Fig. 4), the depth of liquid in which is to be gaged.

Fig. 1 shows. the normal condition 'of the ap arapus when ready to be connected with a esse.

2 shows the apparatus when the. 35

m 'asuring process has commenced and some of; the liquid from the sealing chamber D downward strokes of the tube A and which has passed through the tube C into the seal- :ing chamber D has overcome the head of the liquid in thelatter chambetand been added to the air already in the l ter chamher so as to forcesuificient liqui from the chamber D into the tube E to uncover the lower end of the tube C. No more air can be trapped by the sealing liquid, since when the tube- A is raised, air will fiowback through the tube G into the:tube A above the liquid in the vessel B, thus reducing the pressure in thesealing chamber D until sufficient liquid flows back from the tube E to the sealing chamber D to cover and close the lower end of the tube C, and at each further. stroke of the tube A the air merely flows to and from the compressor without permanently increasing the pressure.

The device is independent of the particw lar form of compressor used, the tube -A shown in the figures representing one formby way of example.

Fig. at shows the apparatus under normal conditions connected with a receptacle K; the depth of the liquid in K can be obtained in lmown manner from a'liquid indicator L, or froma spring pressure gage M, connected with the pipe F, or directly from the compressor apparatus A, B if the latter is transparent, or the safety tube E Iveying the pressuregenerated by the-work ing stroke of the compressor element to said chamber, said means being normally sealed at its lower end by the liquid in said chamnected with the lower portion of said chamher, the cross sections of the safety tube and of the chamber being so proportioned that when the air pressure in the; chamber reaches a predetermined value the lower end of said means is unsealed to permit the back flow of' the air-pressure to said compressor element on the back stroke of the latter.

2. An apparatus for indicating the depth of liquid in a tank or other receptacle, com prising a closed chamber containing a sealing liquid, a pipe connected at one end to the upper portion of said chamber and 'having its other end adapted to be immersed in a tank wherein the depth of liquid is to be measured, a safety tube having its lower end connected to the lower portion of said chamber and its upper end open to the atmosphere, a reciprocating compressor element, means for conveying pressure generated by the working stroke. of said compressor element to said chamber, said means being normally sealed by the liquid in said chamber, the cross-sections of said safety tube and said chamber being so proportioned that,

when the pressure in said chamber reaches a predetermined value, said means is un sealed to permit the backflow of the air pressure in said chamber to said compressor element on the'back stroke of the latter, and

means for indicating the level of the liquid in thesafety tube to show the depth of liquid in the tank. her, a safety tube open to the atmosphere at its upper end and having its lower end con-' In testimony whereof I have signed my name to this specification inthe presence 0! two subscribing witnesses.

- LEONARD MU PHY.

- Witnesses:

.W. E. J onus'roun,

C.-C.Bno!. 

